When it was all over, after a penalty shootout incorporating three successful attempts out of 10, Gus Poyet's players were in a victory scrum in David de Gea's goalmouth and Manchester United will have to reflect that, realistically, their chances of silverware might be over. It has been a difficult, often harrowing season for David Moyes and the late drama here leaves a struggling team with only the Champions League to prevent his first year in charge becoming a total write-off.

They lost a battle of endurance and there was something about the manner of those penalties that tallied with what has happened to United since the managerial handover. Craig Gardner and Steven Fletcher missed the first two for Sunderland and De Gea also kept out Adam Johnson's effort. The problem for United was that Darren Fletcher was the only player in red to put the ball past Vito Mannone. Danny Welbeck wafted his attempt over the crossbar. Adnan Januzaj put the ball into Mannone's arms. Jones did the same as Welbeck and, finally, Mannone saved from Rafael da Silva when the Brazilian needed to score to keep United in it. Marcos Alonso and Ki Sung-yueng had beaten De Gea with Sunderland's second and third penalties and, once again, English football was left to rubberneck at what is happening inside Old Trafford.

It was an epic finale before Sunderland sealed their place at Wembley and a final against Manchester City. United had taken the match into extra-time courtesy of a first-half goal from Jonny Evans and, in an extraordinary 60 seconds, both teams scored in the final moments of the additional 30 minutes. Phil Bardsley, facing his former club, must have thought he had won it for Sunderland with a 20-yard daisy-cutter that De Gea inexplicably allowed through his grasp, Massimo Taibi-style. United, summoning all their old spirit, responded immediately through Javier Hernández. Yet Moyes admitted afterwards that his team had played with little distinction and it was revealing that senior players such as Patrice Evra and Antonio Valencia declined the chance to take a penalty. Poyet, in stark contrast, talked of his players "fighting" for the right to take one.

For Sunderland, those moments ended with delirious scenes among their 9,000-strong following. Poyet may not have the most refined side but they gave everything and had a centre-half, Wes Brown, rolling back the years. It was a victory for spirit and togetherness. There was something remarkable, nonetheless, about what happened to let them back into the game.

It was certainly a horrible mistake from De Gea to let Bardsley's shot through his grasp and over the line, almost in slow motion, to give Sunderland an aggregate lead.

Large swathes of United supporters were already heading for the exits when Januzaj crossed for Hernández to score and there was something of the old, stoic United about that piece of escapology. They actually led 1-0 in the shootout, with Fletcher putting in their second attempt. That, however, was the point when everything unravelled for the home side. They also lost Michael Carrick to an ankle injury and Moyes must wonder when a few silver linings will appear to go with the gathering clouds. Juan Mata's imminent signing is a start because, Januzaj aside, it is clear why Moyes has changed his mind and decided his team need more creativity in attack.

They started the game brightly but it quickly became apparent Sunderland were going to put everything into the night. Lee Cattermole was operating as a shield in front of defence. Fabio Borini could be seen haring back from the left side of attack to help out and that attitude ran through the entire team. Mannone's heroism in the shootout was just an extension of his performance throughout the night.

United had threatened only sporadically before the stooping header from Evans made it 1-0. Fletcher had just struck the post and when Januzaj delivered a corner into the penalty area Welbeck was the first to react. His right-foot effort was miscued but the ball bounced conveniently for Evans, running in at the far post, to beat Mannone from close range.

A more confident team than Sunderland might have shown greater willingness from the start to examine whether United, after four defeats in five games, might be vulnerable, especially with Nemanja Vidic missing. Instead, it was not until the second half that, in danger of going out on the away-goal rule, they started to exert prolonged pressure on their opponents. They lacked a cutting edge but in those moments the Premier League's second-from-bottom side fully matched the champions. Poyet joked afterwards that his team needed to improve their penalty-taking. Nobody at Old Trafford will see the funny side.